No need to include EC parameters explicitly with the private key.

(they are embedded)

acme.sh

@@ -1124,7 +1124,7 @@ _createkey() {
 
   if _isEccKey "$length"; then
     _debug "Using ec name: $eccname"
-    if _opkey="$(${ACME_OPENSSL_BIN:-openssl} ecparam -name "$eccname" -genkey 2>/dev/null)"; then
+    if _opkey="$(${ACME_OPENSSL_BIN:-openssl} ecparam -name "$eccname" -noout -genkey 2>/dev/null)"; then
       echo "$_opkey" >"$f"
     else
       _err "error ecc key name: $eccname"